Gas burner including combustion tunnel



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UNITED STATES PATENT ori-lcs GAS BURNER INCLUDING coMBUs'rIoN TUNNEL This invention relates to wherein combustion is had of Robert M. Buck, Clevel mesne assignments,

ment, Inc., Cleveland,

Delaware and, Ohio, `assignor, by

Affiliated Gas 'Equip- Ohio, a corporation of Application Maiy`26, 1948, Serial No. 29,272 2 Claims. (Cl. 158--99) industrial burners a mixture of gas and air supplied under pressure to a' port or orifice An object of the invention is to provide a long orifice of narrow annular sectional form for high velocity opera tion yet permitting operation at low mixture pressures without flashback.

Another object is to provide such an orifice for employment of a plug replaceable as to size for adjustment of the eiective orice area. For the purpose and as a further object, the invention contemplates employment of a standard outside orifice diameter of standard length, equal substantially to such diameter, so that the general orifice propor ance will not tions and anti-flashback performbe greatly aiected by the diameter of plug employed, all being of the same length.

A further object of the invention is to provide a tunnel form and size, in relation to the port,

such as to pr oduce a sudden reduction of pressure, with turbulence and consequent acceleration of combustion of the stream emerging from the port, and to cause such rapidly expanding stream to intimately contact the tunnel wall just beyond the plug; whereby fuels of different combustion rates may be employed without requiring changes in tunnel dimension.

Another object is' to locate an ignition pipe in r to the burner port that there will be a slight suction at the port before ignition, and ignition may be had with a minimum of mixture in the tunnel.

such relation Further obj ects and advantages will be apparent from the following description taken in connection with the accompanying drawing which is a longitudinal sectional view illustrating an embodiment of the invention.

With reference now to the drawing, the burner comprises bod passageway and including y means having a straight-through a cylindrical restriction or neck portion l with a substantially cylindrical enlargement or tunnel 2 downstream thereof and preferably a convergent portion 3 leading to the neck portion. The tunnel 2 is provided in a refractory block and the other principal parts are preferably of cast metal; as indicated in the drawing and a s is usual in the art.

According to this invention, the length of the restricted por tion I' of the body means is substantially equal to its diameter.

Further, plug means generally indicated at 4 is provided ha ving a cylindrical head portion concentrically disposed in the `body means restriction I'to there effect an annular orifice 5 of effective length equal to its outer diameter, the inner diameter of the orice being determined by the dia-meter of the plug head portion.

The plug head portionis Supported by a shank portion Ii mounted in a spider 1, having collar part 8 clamped Abetween the body portion 3 and a fitting 9 as by Ila-nge bolts not illustrated, a nut I0 securing the plug and spider together.

Preferably, the plug head is of metal and hollow along the orice, 4and includes a refractory part `stream extremity of the plug metal.

The metal and refractory parts of both the body means and the plug head are cemented together in a transverse plane I4 and elsewhere as indicated in the drawing, the plane I4 being located at the downstream end of the port 5,- the cooperative refractoryV parts of plug 4 and tunnel 2 being proportioned as illustrated to provide slight enlargement of theannular passage, im-

downstream of the cylindrical orifice 5 and at the upstream end of the tunnel, as indicated at I5. VThe tunnel 2 thus includes a short divergent section I6, the plug 4 terminates therewithin, with a bluntly rounded or convergent; so that th'epassageway leads from the relatively restricted orice or port 5 into the relatively enlarged tunnel, by way of a relatively short zone of divergence contiguous to each end.

For ignition of the main burner described, the body means is provided with a pipe I1 having a removable closure such as the plug I 8. The inner end of the pipe I'1 is located at the short divergent entrance section I6 of the tunnel 2. By such location, when the closure I8 is removed for ignition purposes, the sudden reduction in presmay be had with a minimum of gas within the tunnel. After ignition, however, such suction is substantially reduced because of the expansion oi' the main stream which takes place in the zone I6.

Characteristics of operation are that the stream emerging from the oriiice and eventually comprising only products of combustion, will "peel olf from the end of the plug and produce a high turbulence just downstream thereof in the zone i6, thereby speeding up combustion in this area. Downstream therebeyond the flame will intimately contact the wall of the tunnel, thus further improving the flame-retaining characteristic.

Also, flashback at low mixture pressures is practically eliminated by the described proportions of the orifice, the arrangement permitting use of plug sizes giving an increase of effective port sizes up to 100 per cent beyond the minimum.

While in the example disclosed the portion l of the body means providing port 5 in the burner passageway has been illustrated and referred to as cylindrical, and constituting a restriction in the body means, it will be appreciated that such portion need not necessarily have a convergent upstream approach thereto, nor need the parts be necessarily cylindrical, although such features are desirable, the former for better flow. characteristics and the latter for ease of manufacture, an essential being that the orice 5 be of narrow Asectional form and substantial length and provide a relatively high velocity therethrough Hereinafter, in the claims, the portion i of the body means may be referred to as .a neck, and terms implying circular sectional form employed nevertheless.

Similarly, while in the specic-formfherein illustrating the invention, `the ,plug means 4 is a composite structure, it will be appreciated that in some instances the plug means might be entirely of metal, and in others entirely of refractory material.

What I claim is: Y

l. In a burner of the class described: body means having a straight through opening leading from an inlet for combustible gas mixture, and including anelongated substantially cylindrical combustion tunnel portion open at its downstream end, an elongated relatively restricted neck portion leading toward the upsteam end of said tunnel portion, and a relatively short flaring Vportion interconnecting said tunnel and neck portions and providing a zone of divergence in flow from said neck portion and to said tunnel portion, and plug means xed within said opening to provide a narrow elongated annular passageway through said neck portion for discharge into said tunnel portion by way of said zone, said plug means extending convergently downstream beyond said neck porton, and having its downstream end located within said zone, and there formed with a ilat central face and a rounded edge about said face.

2. In a burner of the class described: body means having a straight through opening including an elongated substantially cylindrical combustion tunnel portion open at its downstream end, an elongated relatively restricted neck portion leading toward the upstream end of said tunnel portion, and a relatively short flaring portion interconnecting said tunnel and neck portions and providing a zone of divergence in flow from said neck portion and to said tunnel portion, and plug means disposed within said neck portion to there provide a narrow elongated annular port for discharge into said tunnel portion by way of said zone, said plug means extending convergently downstream beyond said neck portion, and having its downstream end located within said zone and formed with a fiat central face and a rounded edge about said face, and said body means having an ignition pipe leading `to said zone, whereby to be responsive to vsuction effect caused by said divergence.

ROBERT M. BUCK.

REFERENCES CITED, The following references are of record in the "file of this patent:

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